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A cost-effective approach was applied to prepare hierarchical porous carbons by simple carbonization and NaCl activation of Artemisia argyi rod at different temperatures. The obtained Artemisia argyi rod–based porous carbon (AARC)-700 material possesses high specific surface area of 1141.8 m2 g−1 and has a hierarchical structure with rich micro-, meso-, and macropores. As electrode for supercapacitor, AARC-700 shows an outstanding electrochemical performance of 348.4 F g−1 at 1 A g−1 in 6 M KOH electrolyte and a superior capacitance of 140 F g−1 at 100 A g−1. At a wide voltage window of 2.0 V, the energy density of the assembled symmetric supercapacitor (AARC-700//AARC-700) at a power density of 2.0 kW kg−1 in 1.0 M Na2SO4 aqueous electrolyte is as high as 32.06 Wh kg−1. Even at a high power density of 40 kW kg−1, a high energy density of 16.67 Wh kg−1 can be achieved. Moreover, the symmetric supercapacitor shows capacitance retention of 99.7% after 20,000 continual charge/discharge cycles at a high current density of 5 A g−1. The results indicate that AARC-700 has bright prospect for application as an electrode material for energy storage. [ABSTRACT FROM AUTHOR]